Is there a difference between Propecia and Proscar? If I'm taking Propecia,rogaine twice a day, and using Nioxin shampoo, am I doing EVERYTHING possible to stop my hair loss? Can I do more? Anyone have success with the laser comb?

Your doing about what you can do at this point without surgery. I've heard the laser comb is a waste of money and only 10% get any results. The only other thing I would suggest is to add 3,000mg of MSM to your regiment. Also add using Nazoral shampoo once a week to your Nioxin daily.
And for hairloss propecia and proscar is the same-- for Proscar you have to cut into 4-5 pieces because it is a 5mg tablet compared to 1mg for Propecia. Proscar because of the splitting of the tablet cause you less money--that's the only difference.
Your regiment might/might not regrow your hair, but it will sure slow the hairloss down or stop it. I've been on this regiment for 6 years and my HT surgeon says this is the only thing saving my crown area (HT was on hairline).